Fuel gauge started working then stopped

[ngzcaz]

Right when I was ready to take off the tank and change the float
( gauge hadn't worked in months, kept reading just above empty ) it
shot up to just under full stayed, there a couple of hours then shut
down again to the just above empty reading even when full.
Originally I thought the float had a pinhole but now I'm stumped, have
no idea whats going on. Anyone encounter a similar situation ?

 

[RobbieD]

Could be in the wiring. What year truck?

 

[ngzcaz]

Its an 1989 Ranger XLT, 2.9 V6 w/ the 5 speed, low miles, always garaged. I tried
wiggling the wires at the gas tank w/ negative results. However, I didnt hang a meter
on it to check for sure. The Ford garage thought it was a float as well, but now I dont
see how it could be if it went up for a couple of hours before it crashed again.

 

[RobbieD]

Yeah, the working a couple of hours and then going back to not working made me think "loose wire". It would be better to use a meter to do the shake-the-harness test, as it will react to changes a lot faster than the guage itself. Sounds like you've got a nice truck; good luck on fixing the annoying guage problem.

 

[MAKG]

While that kind of intermittency has to be electrical, it may or may not be in the float assembly itself. It's just a potentiometer, so you can just read its resistance. Is it reasonable? It's best to do this with the assembly out (sounds like you're almost there) so you can articulate the float.

If you can make it do it again (yeah, I know -- maybe if the stars align), it would be interesting to see if the resistance changes. This might save you dropping the tank.

 

[ngzcaz]

Yeah, I was just under the truck again and wiggled and jiggled and came up zilch.
When I bought it a year ago, it read slightly above empty even when full. Since it had
ridiculously low mileage, I thought it was a float sticking but 10,000 miles later it was
still the same except for a few days ago when it went up for a couple hours then went
down again. I've gone over enough bumps here in NE Pa. that a float should have let
go by now. The underneath looks like new so corrosion is not high on my list.
I'd resort taking it to a garage but they would have to do the same things I could
do only at $ 65.00 an hour... I work cheaper.

 

[Jspafford]

Tell you what, I have an 1989 Bronco II that has a new pump and sending unit and about every 6th startup the guage pegs out past full. As I start driving it slowly works its way back down to the proper level.

 

[MAKG]

I believe "past full" is a dead short. Empty is an open circuit. Either could be anywhere (including in the instrument cluster). But the likely spots are exposed to the weather.

 

[Will]

My B2's gauge has never worked. When I swapped the 2.9/auto for the 4.0/manual, I also swapped the gauge cluster--still didn't work.

Last winter, on about the coldest day, it starting working for the first time in 5 years. A week later it warmed up a bit and quit again. It always shows empty, by the way. I think the sender and pump are together. I'm afraid I'll do real damage trying to fix it so I live with it and just fill it when it shows 300miles.